Shagging FAQ:
ZOMG Spoiler! Click here to view!
If you're a female, you can either shag tedious 'angst fucker' Carth Ana... er... Kaiden; or whiny blue saucetress Liara. And obviously, you want to shag Liara, as her blue fanny is delicious.
If you're a male, you can either shag Liara or actually-not-such-a-bitch-once-you-get-to-know-her Ashley. Which I did during my second playthrough as a male character.
You obviously can't shag Tali, as that would require her to take her suit off and her weakened immune system would probably cause her to be allergic to your fanny batter or something.
You *can* shag the Asari Consort... do as she asks and talk to General Septimus in Chora's Den, and then before going back to the Consort, go to the Elcor/Volus embassy (right next door to the human one) and talk to the Elcor who isn't behind the desk. THEN go see the Consort, and after her 'gift of words' say 'That's it?' to get HAWT HAWT SEXENGS.
As I near the end of what should be my final playthrough (Insanity ftw) a few things I've noted:
-getting the ally achievements isn't as hard as you think - do all the subquests on the Citadel (skip the keeper scanning if you like, it takes forever) and all the subquests on the first four planets. The DLC helps too. Once that's done, you should only have to do one or two assignments on other planets and that'll sort you out. Just ensure if you're going for one of the allies that you get a bit later in the story (Liara) that you go straight for them first and ignore all other distractions until they're in your party.
-biotic powers are absolutely brilliant... don't be afraid to pick a class that uses them out of fear of their being a weedy magic-user class. Lift and then Throw will take care of a lot of very tough foes... hardcases like Geth Destroyers or Krogans are easily dealt with in some levels by lifting them and then using throw to propel them off the nearest cliff.
-especially use damping or throw a Krogan before attempting to deliver the final blow, as they have a nasty habit of using Immunity/Barrier/healing themselves. If they're lolling around on the ground because you've just knocked them flying, they can't do so and you can shoot them to death before they get back up.
-use your powers liberally - Overload and Sabotage are your friends if you have 'em.
-when facing annoying things like Creepers or Husks, remember that if you push the attack button while next to an enemy, you'll pistolwhip them. As these things tend to attack in swarms, doing so will keep them on the ground and prevent their using their attacks.
-try to use more than one weapon... assault rifle and shotgun, or sniper and pistol. You'll have enough points to make it usable, and you'll net the achievements before you know it.
-in between firing the Mako's main cannon, use its machinegun to cause a bit more damage to your target.
-the Mako's jets are more for softening landings than jumping.
-recharging the Mako's shields takes FOREVER... you quite literally have time to go for a shit or make a sandwich or mix up a round of cocktails to fully recharge from empty. Or, save the game and then reload it for a much faster recharge.
-don't be afraid to use medigel - quite often you get some for killing enemies.
-the shield generators (that increase your shield power) are the best armour upgrades by far.
-if an enemy charges you (Krogans and large Geth do this), get your biotic to use lift, throw or singularity and watch them sail over your head.
-Throw affects large groups of enemies.
-prioritise your foes in this order: instadeath dealers (snipers, rocket troopers), tanks (Krogans, Geth Destroyers/Juggernauts/Primes), annoyers (Shock Troopers), everything else. Seriously. Early on, or at higher difficulties, a single hit from a sniper or rocket trooper will kill you in a single hit, making them more dangerous than the big bads. Especially as in a fight you might not spot the rocket/laser sight of the enemy before it's too late to dodge.
SUPER DUPER THERUM (Liara's mission) SPLOITZ
ZOMG Spoiler! Click here to view!
You can take the Mako to the boss battle outside the excavation site. Drive it at the gap, and try to get on your right side. Use a combination of spinning the wheels and firing the jumpjets to work your way through.